Business processing performed in a company is executed in a data center or a private internal network such as an in-house network, and only terminals within the internal network are permitted to access. In recent years, with the spread of ubiquitous environments, there has been a growing need to execute business processing by accessing a private internal network from an external network using a personal computer or mobile terminal via the Internet.
Patent Literature PTL 1 describes a technology in which a terminal on an external network accesses an internal network via a relay server. According to this technology, the relay server comprises a database that stores a user, who operates a terminal, in association with an application server that executes a role of the user (application). The relay server refers to the database in order to manage a session between a terminal operated by a user and an application server. In this technology, a hand shake processing is performed according to a TLS (Transfer Layer Security) protocol, which makes it possible to access while maintaining security.    [PTL 1] Japanese Patent Kokai Publication No. JP2007-036389A